Imaging element and camera system

ABSTRACT

An imaging element includes a plurality of photoelectric conversion sections. The photoelectric conversion sections are arrayed on a substrate to receive light incident through a dual-pass filter that has transmission bands for visible light and a predetermined range of near-infrared light. The photoelectric conversion sections include a visible light photoelectric conversion section and a near-infrared light photoelectric conversion section. The visible light photoelectric conversion section includes a red light photoelectric conversion section, a green light photoelectric conversion section, and a blue light photoelectric conversion section.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/577,733, filed Sep. 20, 2019, which is a continuation of U.S. patentapplication Ser. No. 16/064,563, filed Jun. 21, 2018, now U.S. Pat. No.10,461,106, which is a national stage application under 35 U.S.C. 371and claims the benefit of PCT Application No. PCT/JP2016/080950 havingan international filing date of Oct. 19, 2016, which designated theUnited States, which PCT application claimed the benefit of JapanesePatent Application No. 2016-017900 filed Feb. 2, 2016, the entiredisclosures of each of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an imaging element and a camerasystem.

BACKGROUND ART

In the past, an image pickup device capable of simultaneously acquiringa color image and a near-infrared image was proposed. Disclosed, forexample, in JP 1998-210486 A (PTL 1) is a technology for dividingincoming light into four types of light, namely, near-infrared light,red light, green light, and blue light, by using, for example, a coldmirror or a dichroic mirror and acquiring an image signal of each colorby receiving the four types of light with respective independentlight-receiving means.

CITATION LIST Patent Literature

[PTL 1]

JP 1998-210486 A

SUMMARY Technical Problem

In recent years, it is demanded that camera systems used, for example,with portable electronic devices be thinned. The camera systems cannotbe thinned as needed by a configuration for dividing incoming light intofour types of light, namely, near-infrared light, red light, greenlight, and blue light, and receiving the four types of light withrespective independent light-receiving means.

In view of the above circumstances, an object of the present inventionis to provide an imaging element having a one-lens-one-sensor structurecapable of simultaneously acquiring a color image and a near-infraredimage. Another object of the present invention is to provide a camerasystem that uses such an imaging element.

Solution to Problem

In accomplishing the above objects, according to a first aspect of thepresent disclosure, there is provided an imaging element including aplurality of photoelectric conversion sections. The photoelectricconversion sections are arrayed on a substrate to receive light incidentthrough a dual-pass filter that has transmission bands for visible lightand a predetermined range of near-infrared light. The photoelectricconversion sections include a visible light photoelectric conversionsection and a near-infrared light photoelectric conversion section. Thevisible light photoelectric conversion section includes a red lightphotoelectric conversion section, a green light photoelectric conversionsection, and a blue light photoelectric conversion section.

In accomplishing the above objects, according to the first aspect of thepresent disclosure, there is provided a camera system including anoptical section, an imaging element, and a signal processing section.The optical section forms an image of a subject. The imaging elementincludes a plurality of photoelectric conversion sections that arearrayed on a substrate to receive light incident through a dual-passfilter having transmission bands for visible light and a predeterminedrange of near-infrared light. The signal processing section processessignals from the photoelectric conversion sections. The photoelectricconversion sections include a visible light photoelectric conversionsection and a near-infrared light photoelectric conversion section. Thesignal processing section performs computation after changing a matrixcoefficient in accordance with the position of a photoelectricconversion section. The matrix coefficient is used to performcomputation for eliminating the influence of near-infrared lightincluded in a signal from the visible light photoelectric conversionsection.

Advantageous Effects of Invention

One imaging element according to the present disclosure makes itpossible to simultaneously acquire a color image and a near-infraredimage. Further, as described later, it is possible to reduce thedifference, for example, in color tone between the central andperipheral parts of an image to be captured. The advantageous effectsdescribed in this specification are merely illustrative and notrestrictive. The present disclosure can provide additional advantageouseffects.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram illustrating an imagingelement according to a first embodiment and a camera system that usessuch an imaging element.

FIG. 2 is a schematic plan view illustrating, for example, an imagingarea of the imaging element.

FIG. 3 is a schematic graph illustrating the spectral transmittance of adual-pass filter.

FIG. 4 is a schematic graph illustrating the emission spectrum of anear-infrared light source section.

FIG. 5 is a schematic graph illustrating the spectral transmittance ofcolor filters.

FIG. 6 is a schematic graph illustrating the spectral transmittance ofnear-infrared absorption filters cited as a reference example.

FIG. 7 is a schematic graph illustrating the spectral transmittance of acombination of the color filters and the near-infrared absorptionfilters cited as the reference example.

FIG. 8 is a schematic graph illustrating the spectral transmittance of acombination of the dual-pass filter, the color filters, and thenear-infrared absorption filters cited as the reference example.

FIG. 9 is a schematic graph illustrating the overall spectraltransmittance at the center of the imaging area of the imaging elementin a case where the near-infrared absorption filters cited as thereference example are used.

FIG. 10 is a schematic graph illustrating the overall spectraltransmittance at a part of the imaging area of the imaging element wherethe CRA is 30 degrees in the case where the near-infrared absorptionfilters cited as the reference example are used.

FIG. 11 is a schematic perspective view illustrating the relationbetween a first near-infrared absorption layer and a secondnear-infrared absorption layer that are included in a near-infraredabsorption filter used in the first embodiment.

FIG. 12 is a schematic partial end view of the imaging element accordingto the first embodiment.

FIG. 13 is a schematic graph illustrating the spectral transmittance ofthe first near-infrared absorption layer.

FIG. 14 is a schematic graph illustrating the spectral transmittance ofthe second near-infrared absorption layer.

FIG. 15 is a schematic graph illustrating the spectral transmittance ofthe near-infrared absorption filters used in the first embodiment.

FIG. 16 is a schematic graph illustrating the overall spectraltransmittance at the center of the imaging area of the imaging elementin a case where the near-infrared absorption filters according to thefirst embodiment are used.

FIG. 17 is a schematic graph illustrating the overall spectraltransmittance at a part of the imaging area of the imaging element wherethe CRA is 30 degrees in the case where the near-infrared absorptionfilters according to the first embodiment are used.

FIG. 18 is a schematic cross-sectional view illustrating a configurationof an optical filter that includes the dual-pass filter and is used in athird embodiment.

FIG. 19 is a schematic graph illustrating the spectral transmittance ofa first infrared absorption layer included in the optical filterincluding the dual-pass filter.

FIG. 20 is a schematic graph illustrating the spectral transmittance ofa second infrared absorption layer included in the optical filterincluding the dual-pass filter.

FIG. 21 is a schematic graph illustrating the spectral transmittance ofthe optical filter that includes the dual-pass filter and is used in thethird embodiment.

FIG. 22 is a schematic partial end view of the imaging element that ispresented to illustrate a first modification of the third embodiment.

FIG. 23 is a schematic partial end view of the imaging element that ispresented to illustrate a second modification of the third embodiment.

FIG. 24 is a schematic partial end view of the imaging element that ispresented to illustrate a third modification of the third embodiment.

FIG. 25 are schematic plan views illustrating the arrangement of thecolor filters and near-infrared absorption filters in the firstembodiment. FIG. 25A is a schematic plan view illustrating thearrangement of the color filters in the first embodiment. FIG. 25B is aschematic plan view illustrating the arrangement of the near-infraredabsorption filters in the first embodiment.

FIG. 25C is a schematic plan view illustrating the arrangement ofphotoelectric conversion sections that are involved in the acquisitionof a near-infrared image in the first embodiment.

FIG. 26 are schematic plan views illustrating the arrangement of thecolor filters and near-infrared absorption filters in the fourthembodiment. FIG. 26A is a schematic plan view illustrating thearrangement of the color filters in the fourth embodiment. FIG. 26B is aschematic plan view illustrating the arrangement of the near-infraredabsorption filters in the fourth embodiment. FIG. 26C is a schematicplan view illustrating the arrangement of the photoelectric conversionsections that are involved in the acquisition of a near-infrared imagein the fourth embodiment.

FIG. 27 is a schematic partial end view of the imaging element.

FIG. 28 are schematic plan views illustrating the arrangement of thecolor filters and near-infrared absorption filters in a fifthembodiment. FIG. 28A is a schematic plan view illustrating thearrangement of the color filters in the fifth embodiment. FIG. 28B is aschematic plan view illustrating the arrangement of the near-infraredabsorption filters in the fifth embodiment. FIG. 28C is a schematic planview illustrating the arrangement of the photoelectric conversionsections that are involved in the acquisition of a near-infrared imagein the fifth embodiment.

FIG. 29 are diagrams illustrating the arrangement of the color filtersand near-infrared absorption filters in the fifth embodiment in a casewhere the arrangement of the near-infrared absorption filters islimited. FIG. 29A is a schematic plan view illustrating the arrangementof the color filters. FIG. 29B is a schematic plan view illustrating thearrangement of the near-infrared absorption filters. FIG. 29C is aschematic plan view illustrating the arrangement of the photoelectricconversion sections that are involved in the acquisition of anear-infrared image.

FIG. 30 are schematic plan views illustrating the arrangement of thecolor filters and near-infrared absorption filters in a sixthembodiment. FIG. 30A is a schematic plan view illustrating thearrangement of the color filters in the sixth embodiment. FIG. 30B is aschematic plan view illustrating the arrangement of the near-infraredabsorption filters in the sixth embodiment. FIG. 30C is a schematic planview illustrating the arrangement of the photoelectric conversionsections that are involved in the acquisition of a near-infrared imagein the sixth embodiment.

FIG. 31 are diagrams illustrating the arrangement of the color filtersand near-infrared absorption filters in the sixth embodiment in a casewhere the arrangement of the near-infrared absorption filters islimited. FIG. 31A is a schematic plan view illustrating the arrangementof the color filters. FIG. 31B is a schematic plan view illustrating thearrangement of the near-infrared absorption filters. FIG. 31C is aschematic plan view illustrating the arrangement of the photoelectricconversion sections that are involved in the acquisition of anear-infrared image.

FIG. 32 is a schematic partial end view of the imaging element in aseventh embodiment.

FIG. 33 is a schematic partial end view of the imaging element in aneighth embodiment.

DESCRIPTION OF EMBODIMENTS

The present disclosure will now be described on the basis of embodimentswith reference to the accompanying drawings. The present disclosure isnot limited to the embodiments. Various numerical values and materialsmentioned in conjunction with the embodiments are illustrative and notrestrictive. In the following description, identical elements andelements having the same functionality are designated by the samereference signs and will not be redundantly described. The descriptionwill be given in the following order.

1. Overall description of an imaging element according to a first aspectof the present disclosure and a camera system according to the firstaspect of the present disclosure

2. First Embodiment

3. Second Embodiment

4. Third Embodiment

5. Fourth Embodiment

6. Fifth Embodiment

7. Sixth Embodiment

8. Seventh Embodiment

9. Eighth Embodiment

10. Other

[Overall Description of the Imaging Element According to the FirstAspect of the Present Disclosure and the Camera System According to theFirst Aspect of the Present Disclosure]

As described above, the imaging element according to the first aspect ofthe present disclosure includes a plurality of photoelectric conversionsections. The photoelectric conversion sections are arrayed on asubstrate to receive light incident through a dual-pass filter that hastransmission bands for visible light and a predetermined range ofnear-infrared light. The photoelectric conversion sections include avisible light photoelectric conversion section and a near-infrared lightphotoelectric conversion section. The visible light photoelectricconversion section includes a red light photoelectric conversionsection, a green light photoelectric conversion section, and a bluelight photoelectric conversion section.

In the imaging element according to the first aspect of the presentdisclosure, the red light photoelectric conversion section, the greenlight photoelectric conversion section, the blue light photoelectricconversion section, and the near-infrared light photoelectric conversionsection may be arrayed in a mosaic pattern.

In the imaging element according to the first aspect of the presentdisclosure including the above-mentioned various preferred embodiments,the green light photoelectric conversion section may be set to a higherplacement ratio than the other photoelectric conversion sections.

In the imaging element according to the first aspect of the presentdisclosure including the above-mentioned various preferred embodiments,the near-infrared light photoelectric conversion section may include awhite light photoelectric conversion section.

In the imaging element according to the first aspect of the presentdisclosure including the above-mentioned various preferred embodiments,the substrate may have a shallow trench structure for separatingneighboring photoelectric conversion sections.

In the imaging element according to the first aspect of the presentdisclosure including the above-mentioned various preferred embodiments,a near-infrared absorption filter may be selectively disposed on a lightincident surface of the photoelectric conversion sections incorrespondence with the visible light photoelectric conversion section.Setup may be performed so that a near-infrared light absorption bandprovided by the near-infrared absorption filter includes a near-infraredlight transmission band of the dual-pass filter and extends toward ashort wavelength side.

In the above case, the near-infrared light absorption band provided bythe near-infrared absorption filter may be set to include thenear-infrared light transmission band of the dual-pass filter even in acase where the near-infrared light transmission band is shifted towardthe short wavelength side due to oblique light incidence.

In the above case, the near-infrared absorption filter may include atleast two different coloring substances that differ in near-infraredlight absorption characteristics.

In the above case, the near-infrared absorption filter may include afirst near-infrared absorption layer and a second near-infraredabsorption layer. The first near-infrared absorption layer may includeone of the two different coloring substances. The second near-infraredabsorption layer may include the remaining one of the two differentcoloring substances. Alternatively, the near-infrared absorption filtermay include a single layer.

In the imaging element according to the first aspect of the presentdisclosure including the above-mentioned various preferred embodiments,the near-infrared absorption filter may be selectively disposed incorrespondence with the red light photoelectric conversion section, thegreen light photoelectric conversion section, and the blue lightphotoelectric conversion section. Alternatively, the near-infraredabsorption filter may be selectively disposed for the blue lightphotoelectric conversion section in the visible light photoelectricconversion section.

In the above case, a color filter and the near-infrared absorptionfilter may be stacked over the light incident surface of the visiblelight photoelectric conversion section.

In the above case, at least a part of the near-infrared absorptionfilter may be embedded into an opening in a light-shielding layer thatseparates neighboring photoelectric conversion sections.

Further, the imaging element according to the first aspect of thepresent disclosure may include a near-infrared absorption layer that isdisposed integrally with the dual-pass filter or disposed separatelyfrom the dual-pass filter. The near-infrared light transmission band ofthe dual-pass filter may be sandwiched between a first absorption bandand a second absorption band. The first absorption band and the secondabsorption band may be provided for near-infrared light in thenear-infrared absorption layer.

In the above case, the near-infrared absorption layer may include atleast two different coloring substances that differ in near-infraredlight absorption characteristics.

In the above case, the near-infrared absorption layer may include afirst near-infrared absorption layer and a second near-infraredabsorption layer. The first near-infrared absorption layer may includeone of the two different coloring substances. The second near-infraredabsorption layer may include the remaining one of the two differentcoloring substances. Alternatively, the near-infrared absorption layermay include a single layer containing the two different coloringsubstances that differ in near-infrared light absorptioncharacteristics.

In a case where, for example, the first absorption band is positionedtoward the long wavelength side as compared to the second absorptionband, the near-infrared light transmission band of the dual-pass filtercan be sandwiched between the first absorption band and the secondabsorption band by performing setup in such a manner that the shortwavelength side of the first absorption band substantially coincideswith or partly overlaps with the long wavelength side of thenear-infrared light transmission band of the dual-pass filter, and thatthe long wavelength side of the second absorption band substantiallycoincides with or partly overlaps with the short wavelength side of thenear-infrared light transmission band of the dual-pass filter.

As the imaging element according to the present disclosure including theabove-described preferred embodiments and configurations and as theimaging element used in the camera system (these imaging elements may behereinafter simply referred to as the “imaging elements or other similarelements according to the present disclosure”), for example, a CCD imagesensor or a CMOS image sensor may be used. These image sensors may be ofa front-illuminated type or of a back-illuminated type. Further, as adevice using the imaging element or camera system according to thepresent disclosure, for example, a digital still camera, a digital videocamera, a camcorder, a surveillance camera, a vehicle-mounted camera, asmartphone camera, a user interface camera for gaming, and a biometricauthentication camera may be used. These devices are capable of not onlyacquiring a normal visible light image but also simultaneously acquiringa near-infrared image.

As a substrate on which the photoelectric conversion sections areformed, a semiconductor substrate and, in particular, a siliconsemiconductor substrate may be used. The silicon semiconductor substrateabsorbs not only visible light but also light having a wavelength ofapproximately 1 μm. Therefore, photodiodes, phototransistors, and otherphotoelectric conversion elements formed on the silicon substrate arecapable of photoelectrically converting not only visible light but alsonear-infrared light.

The dual-pass filter may include, for example, a cutoff band absorptionlayer for absorbing a boundary zone (cutoff band) between visible lightand near-infrared light and a dielectric multilayer film having severalten to hundred and several ten layers for controlling the near-infraredlight transmission band. As a coloring substance included in the cutoffband absorption layer, the near-infrared absorption filter, and thenear-infrared absorption layer, a well-known pigment or dye can be used.For example, a squarylium-based compound, a phthalocyanine-basedcompound, or a cyanine-based compound may be used. From the viewpoint oflight resistance and heat resistance, it is particularly preferable thatthe squarylium-based compound be used.

As the color filter, a filter layer transmitting a specific wavelength,such as red, green, or blue, may be used. The color filter may includean organic material layer that uses a pigment, a dye, or other organiccompound. In some cases, a complementary color filter transmitting aspecific wavelength, such as cyan, magenta, or yellow, may be used.

A region between neighboring photoelectric conversion sections, forexample, of the imaging element according to the present disclosure mayinclude a light-shielding layer including, for example, chrome (Cr),copper (Cu), aluminum (Al), tungsten (W), or other metal material or adielectric material. This configuration effectively prevents light fromleaking into the neighboring photoelectric conversion sections. Itshould be noted that materials similar to the above-mentioned ones maybe embedded in the shallow trench structure formed on the substrate.

The color filter, the near-infrared absorption filter, the near-infraredabsorption layer, the cutoff band absorption layer, and, for example, aninterlayer insulating layer and a planarization layer that are included,for example, in the imaging element can be formed on the basis ofwell-known methods such as various chemical vapor deposition methods(CVD methods), a coating method, and various physical vapor depositionmethods (PVD methods). Further, as a patterning method, a combination oflithography technology and etching technology or a well-known methodsuch as a liftoff method may be used.

For improved light collection efficiency, for example, the imagingelement according to the present disclosure may be formed so that anon-chip lens (OCL) is disposed above the photoelectric conversionsections.

In a case where the interlayer insulating layer and the planarizationlayer are to be formed by using a transparent material, for example, aninsulating material having no light absorption characteristics may beused. More specifically, the material to be used may be, for example, aSiO_(x)-based material (a material forming a silicon-based oxide film),a low-permittivity insulating material such as SiN, SiON, SiOC, SiOF,SiCN, or organic SOG, polyimide-based resin, or fluorine-based resin.This also holds true for the OCL.

Conditions specified by various equations in this specification are metnot only in a case where the equations are strictly established in amathematical manner, but also in a case where the equations aresubstantially established. As regards the establishment of theequations, various variations resulting from the design or manufactureof the imaging element or the camera system are permitted.

In the following description, graphs are referenced to explain about,for example, spectral characteristics. However, these graphs areschematic and are not indicative, for example, of accurate spectralcharacteristics. The shapes of the graphs are also schematic.

First Embodiment

A first embodiment relates to an imaging element according to thepresent disclosure and to a camera system that uses such an imagingelement.

FIG. 1 is a schematic configuration diagram illustrating the imagingelement according to the first embodiment and the camera system thatuses the imaging element. FIG. 2 is a schematic plan view illustrating,for example, an imaging area of the imaging element.

The camera system 1 includes an optical section (imaging lens) 200, animaging element 100, and a signal processing section 300. The opticalsection 200 forms an image of a subject. The imaging element 100includes a plurality of photoelectric conversion sections 40 that arearrayed on a substrate to receive light incident through a dual-passfilter 70 having transmission bands for visible light and apredetermined range of near-infrared light. The signal processingsection 300 processes signals from the photoelectric conversion sections40.

The photoelectric conversion sections 40 include a visible lightphotoelectric conversion section and a near-infrared light photoelectricconversion section.

The visible light photoelectric conversion section 40 includes a redlight photoelectric conversion section, a green light photoelectricconversion section, and a blue light photoelectric conversion section.The red light photoelectric conversion section, the green lightphotoelectric conversion section, the blue light photoelectricconversion section, and the near-infrared light photoelectric conversionsection are arrayed in a mosaic pattern.

A near-infrared absorption filter 50 is selectively disposed on a lightincident surface of the photoelectric conversion sections 40 incorrespondence with the visible light photoelectric conversion section40. More specifically, the near-infrared absorption filter 50 isselectively disposed in correspondence with the red light photoelectricconversion section, the green light photoelectric conversion section,and the blue light photoelectric conversion section.

Setup is performed so that a near-infrared light absorption bandprovided by the near-infrared absorption filter 50 includes anear-infrared light transmission band of the dual-pass filter 70 andextends toward a short wavelength side. More details will be given laterwith reference to FIGS. 11 to 17.

Light transmitted through the dual-pass filter 70 reaches thephotoelectric conversion sections 40 through a color filter 60 and thenear-infrared absorption filter 50. The imaging element 100 includes,for example, mega pixels. For convenience of explanation, however, FIG.1 depicts four pixels that form one unit. The sign “IRA,” which isassigned to the near-infrared absorption filter 50, denotes“near-infrared absorption.” This also holds true for the other drawings.In the imaging area 11 depicted in FIG. 2, the photoelectric conversionsections 40, the color filter 60, and the near-infrared absorptionfilter 50 are disposed, for example, in an array. It should be notedthat the array is not depicted in FIG. 2. The chief ray angle is 0degrees at the center of the imaging area 11. The longer the distancefrom the center of the imaging area 11, the greater the chief ray angle.

The dual-pass filter 70 depicted in FIG. 1 is configured so that thecutoff band absorption layer absorbs the wavelength region between 650nm and 750 nm and that the dielectric multilayer film controls thespectral characteristics of the near-infrared light transmission band.FIG. 3 is a schematic graph illustrating the spectral transmittance ofthe dual-pass filter. The following description assumes that the centerof the near-infrared light transmission band of the dual-pass filter 70has a wavelength of 850 nm, and that the width of the near-infraredlight transmission band is set to approximately 80 nm. However, thepresent disclosure is not limited to such a configuration.

The camera system 1 depicted in FIG. 1 further includes a near-infraredlight source section 400 that includes, for example, an LED forirradiating near-infrared light within a certain wavelength range ontothe subject. An exemplary spectrum of the near-infrared light sourcesection 400 is depicted in FIG. 4. The typical emission wavelengthbandwidth of an available near-infrared LED is approximately several tennm. It is assumed that the center of the emission wavelength of such anear-infrared LED coincides with the center of the near-infrared lighttransmission band of the dual-pass filter 70. On the basis of theambient light including near-infrared light and of the near-infraredlight within a predetermined wavelength range from the near-infraredlight source section 400, light reflected from the subject is incidenton the optical section 200.

It should be noted that the near-infrared light transmission band of thedual-pass filter 70 and the emission wavelength of the near-infraredlight source section 400 should be selected in accordance with thespectral reflectance characteristics of an observation target. For irisauthentication, near-infrared light having a wavelength of approximately800 to 900 nm is used.

First of all, photoelectric conversion of red, green, and blue lightwill be described. The dual-pass filter 70 functions so that visiblelight within a predetermined range and near-infrared light within apredetermined range, which are included in the light reflected from thesubject, reach the color filter 60 and are subjected to colorseparation.

FIG. 5 is a schematic graph illustrating the spectral transmittance ofthe color filters. The illustrated spectral transmittance is obtained ina case where red, green, blue, and near-infrared light color filters aredeposited to form a film on a transparent base material. According tothe studies conducted by the inventors of the present disclosure, it isconfirmed that the film thickness of a near-infrared light color filterneeds to be approximately two times the film thickness of the othercolor filters in order to permit the near-infrared light color filter tosufficiently block the visible light. As indicated in the drawing, colorfilters marketed for imaging elements generally exhibit a transmittanceof approximately 100 percent at wavelengths longer than 800 nm.

Consequently, light transmitted through a red color filter (which may bedesignated by the reference sign 60 _(R)) includes near-infrared lightwithin a predetermined range in addition to red visible light, lighttransmitted through a green color filter (which may be designated by thereference sign 60 _(G)) includes near-infrared light within apredetermined range in addition to green visible light, and lighttransmitted through a blue color filter (which may be designated by thereference sign 60 _(B)) includes near-infrared light within apredetermined range in addition to blue visible light.

Thus, light transmitted through the red, green, and blue color filters60 is passed to near-infrared absorption filters 50 disposed incorrespondence with red, green, and blue light photoelectric conversionsections 40 in order to reduce a near-infrared light component, and thenconveyed to the photoelectric conversion sections 40 and subjected tophotoelectric conversion. Accordingly, signals representative of theintensities of red light, green light, and blue light, which areincluded in the light reflected from the subject, are outputted from thered, green, and blue light photoelectric conversion sections 40.

The photoelectric conversion of near-infrared light will now bedescribed. A color filter corresponding to the near-infrared lightphotoelectric conversion section 40 (which may be designated by thereference sign 60 _(IR)) includes a visible light absorbing materialthat absorbs visible light and transmits near-infrared light. Lighttransmitted through the dual-pass filter 70 is passed to the colorfilter 60 _(1R) in order to reduce a visible light component, and thenconveyed to the near-infrared light photoelectric conversion section 40and subjected to photoelectric conversion.

In order to facilitate the understanding of the present disclosure, aconfiguration in which the near-infrared light absorption band providedby the near-infrared absorption filter substantially coincides with thenear-infrared light transmission band of the dual-pass filter 70 isdescribed below as a reference example. Further, some necessaryconsiderations are also described below.

The near-infrared absorption filters may include, for example, one orseveral layers containing a coloring substance or include a dielectricmultilayer film having several tens of layers. However, from theviewpoint where the near-infrared absorption filters are selectivelydisposed in correspondence with the red, green, and blue lightphotoelectric conversion sections 40, it is preferable that thenear-infrared absorption filters include one or several layerscontaining a coloring substance (infrared absorbing material). Further,it is preferable from the viewpoint of manufacture that the thickness ofthe near-infrared absorption filters be substantially equal to thethickness of the color filters 60 (e.g., several hundred nm to one μm).

In a case where the near-infrared absorption filters are formed, forexample, by spin-coating a material containing a coloring substance, amaterial such as cyanine, phthalocyanine, or squarylium may be used as acoloring substance. FIG. 6 is a schematic graph illustrating thespectral transmittance of the near-infrared absorption filters formed inthe above manner. The center wavelength of the near-infrared lightabsorption band can be adjusted by changing the molecular design of thecoloring substance, for example, the molecular framework of the coloringsubstance and the configuration of substituents.

Studies conducted by the inventors in relation to the above-mentionedcoloring substance have revealed that visible region absorption occursdue to the main framework of a material (portion A in FIG. 6), and thatan increase in density or film thickness causes a visible regiontransmittance deterioration of several ten percent and incurssignificant sensitivity degradation of the visible region.

Consequently, it has been revealed that the coloring substance densityand film thickness of a layer containing an infrared absorbing materialneed to be set within a permissible range of visible regiontransmittance deterioration. As a result, it has been found that theinfrared absorption rate remains at approximately 50% to 90%. Further,it has been found that the absorption wavelength bandwidth of theaforementioned infrared absorbing material is approximately 50 nm whendefined in half width and at the same level as the near-infrared lighttransmission bandwidth of the dual-pass filter 70.

When the near-infrared absorption filters cited as the reference examplehaving characteristics depicted in FIG. 6 are combined with the colorfilters 60 having the characteristics depicted in FIG. 5, the spectraltransmittance is expressed as depicted in FIG. 7. Further, when thedual-pass filter 70 having the characteristics depicted in FIG. 3 isadditionally combined, the spectral characteristics are expressed asdepicted in FIG. 8.

A mixed color resulting from near-infrared light during the use of thenear-infrared absorption filters cited as the reference example and itselimination will now be described. FIG. 9 is a schematic graphillustrating the overall spectral transmittance at the center of theimaging area of the imaging element (i.e., a portion having a CRA of 0degrees) in a case where the near-infrared absorption filters cited asthe reference example are used. The graph itself is similar to the onedepicted in FIG. 8.

In a case where the near-infrared absorption filters cited as thereference example are used, portion B in FIG. 9 is a mixed colorcomponent that is obtained when visible light is mixed withnear-infrared light. Further, portion C in FIG. 9 is a mixed colorcomponent that is obtained when near-infrared light is mixed withvisible light. Here, it is assumed that the transmittance of portion Bis 20%, for example. The above-mentioned mixed color can be eliminatedby performing matrix computation.

For example, an original signal from the red light photoelectricconversion section 40 is represented by the sign R_(ori), an originalsignal from the green light photoelectric conversion section 40 isrepresented by the sign G_(ori), an original signal from the blue lightphotoelectric conversion section 40 is represented by the sign B_(ori),and an original signal from the near-infrared light photoelectricconversion section 40 is represented by the sign IR_(ori). Further, acorrected red light signal is represented by the sign R_(cvt), acorrected green light signal is represented by the sign G_(cvt)% acorrected blue light signal is represented by the sign B_(cvt), and acorrected near-infrared light signal is represented by the signIR_(cvt). The corrected signals can be obtained by performing matrixcomputation in the signal processing section 300 as indicated inEquation (1) below.

$\begin{matrix}{\begin{bmatrix}R_{cvt} \\G_{cvt} \\B_{cvt} \\{IR}_{cvt}\end{bmatrix} = {\begin{bmatrix}1.02 & 0 & 0 & {- 0.20} \\0.02 & 1.01 & 0 & {- 0.20} \\0.03 & 0.01 & 1.00 & {- 0.20} \\{- 0.12} & 0 & {- 0.05} & 1.02\end{bmatrix}\begin{bmatrix}R_{ori} \\G_{ori} \\B_{ori} \\{IR}_{{ori}\;}\end{bmatrix}}} & (1)\end{matrix}$

When attention is paid, for example, to the corrected red light signalR_(cvt), the following computation is performed:R _(cvt)=1.02×R _(ori)−0.2×IR _(ori)This indicates that the output of the near-infrared light photoelectricconversion section 40 will be reduced by 20 percent.

If the transmittance of portion B in FIG. 9 is 100%, the followingcomputation needs to be performed in order to eliminate a mixed colorresulting from near-infrared light:R _(cvt)=1.02×R _(ori)=1.0×IR _(ori)This indicates that the output of the near-infrared light photoelectricconversion section 40 will be reduced to zero. However, the signalR_(ori) and the signal IR_(ori) each include noise induced byphotoelectric conversion. Therefore, the level of noise included inR_(cvt) is substantially doubled in a qualitative sense so that the S/Nratio deteriorates by approximately 6 dB. In a case where imaging isperformed, for example, under ambient light that includes a relativelylarge amount of near-infrared light such as halogen lamp light oroutdoor light, several dB deterioration caused by the above correctioncomputation poses an image equality problem.

Meanwhile, in the first embodiment, computation is performed so as toreduce the output of the near-infrared light photoelectric conversionsection 40 by 20 percent. Therefore, the noise level is merely increasedapproximately 1.2 times. Consequently, it is possible to suppress S/Nratio deterioration caused by the correction computation.

Further, when attention is paid to the corrected near-infrared lightsignal IR_(cvt), computation is performed as indicated by the equationIR_(cvt)=−0.12×R_(ori)−0.05×B_(ori)+1.02×R_(ori). This eliminates avisible light component indicated by portion B in FIG. 9.

The mixed color resulting from near-infrared light during the use of thenear-infrared absorption filters cited as the reference example and itselimination have been described. In reality, however, a color differenceoccurs between the center and periphery of a screen due to the CRAdifference between the center and periphery of the imaging element 100.A detailed description is given below.

The spectral characteristics of the near-infrared region of thedual-pass filter 70 are controlled by a dielectric multilayer film.Therefore, the spectral characteristics of the near-infrared region varywith the angle of incidence of light. In a qualitative sense, thespectral characteristics shift toward the short wavelength side due tooblique incidence. In a case where a typical multilayer film design isadopted, the spectral characteristics shift by approximately 1 nm towardthe short wavelength side when the angle of incidence increases by 1degree.

FIG. 10 is a schematic graph illustrating the overall spectraltransmittance at a part of the imaging area of the imaging element wherethe CRA is 30 degrees in a case where the near-infrared absorptionfilters cited as the reference example are used.

As is obvious from a comparison between FIGS. 9 and 10, the mixed colorcomponent that is obtained when visible light is mixed withnear-infrared light as indicated by portion B′ in FIG. 10 is greaterthan the mixed color component indicated by portion B in FIG. 9.Therefore, an insufficient correction results in a case where matrixcomputation is performed as indicated in Equation (1) above. The resultof simulation indicates that the ΔEab difference in a 24-color Macbethchart between a CRA of 0 degrees and a CRA of 30 degrees is 17 atmaximum in patch No. 16 and 5 on the average of 24 colors. Thisrepresents a level at which a distinct color difference is recognizedbetween the center and periphery of a screen.

The fact that a color difference arises from the difference in CRAduring the use of a configuration cited as the reference example hasbeen described.

In order to resolve the color difference caused by the above-describeddifference in CRA, the first embodiment is configured so that thenear-infrared light absorption band provided by the near-infraredabsorption filter 50 includes the near-infrared light transmission bandof the dual-pass filter 70 and extends toward the short wavelength side.More specifically, the near-infrared light absorption band provided bythe near-infrared absorption filter 50 includes the near-infrared lighttransmission band of the dual-pass filter 70 even in a case where thenear-infrared light transmission band is shifted toward the shortwavelength side due to oblique incidence of light.

The first embodiment will now be described in detail with reference toFIGS. 11 to 17.

In the first embodiment, the near-infrared absorption filters 50 includeat least two different coloring substances that differ in near-infraredlight absorption characteristics. Therefore, setup can be performed sothat the near-infrared light absorption band provided by thenear-infrared absorption filters 50 includes the near-infrared lighttransmission band of the dual-pass filter 70 and extends toward theshort wavelength side.

More specifically, as depicted in FIG. 11, the near-infrared absorptionfilter 50 includes a first near-infrared absorption layer 50A and asecond near-infrared absorption layer 50B. The first near-infraredabsorption layer 50A includes one of the two different coloringsubstances. The second near-infrared absorption layer 50B includes theremaining one of the two different coloring substances.

FIG. 12 is a schematic partial end view of the imaging element accordingto the first embodiment. For convenience of illustration, it is assumedthat red, green, blue, and near-infrared light elements are arrayed in arow. The color filters 60 and the near-infrared absorption filters 50are stacked over the light incident surface of the visible lightphotoelectric conversion section 40.

The photoelectric conversion sections 40 are formed over a semiconductorsubstrate 10 that includes, for example, silicon. It should be notedthat photodiodes and other elements included in the photoelectricconversion sections 40 and the wiring and other elements connected tothe photoelectric conversion sections 40 are omitted from the drawing.The reference sign 30 denotes a light-shielding layer that is disposedbetween the neighboring photoelectric conversion sections 40. Thereference sign 20 denotes a planarization layer that covers, forexample, the light-shielding layer 30. The first near-infraredabsorption layer 50A and the second near-infrared absorption layer 50B,which are included in the near-infrared absorption filters 50, aredisposed at positions corresponding to the red, green, and blue lightphotoelectric conversion sections 40. Additionally, the red, green, andblue color filters 60 (60 _(R), 60 _(G), 60 _(B)) are formed over thenear-infrared absorption filters 50. The near-infrared light colorfilter (60 _(IR)) is formed over the planarization layer 20. Further, atransparent material layer 61 is formed to cover the entire surface ofthe color filters 60. The surface of the transparent material layer 61is shaped like a lens corresponding to each photoelectric conversionsection 40 in order to form an on-chip lens 62. Although not depicted inthe drawing, the dual-pass filter 70 is disposed above the on-chip lens62.

The color filters 60 and the near-infrared absorption filters 50 can beformed by configuring their material layers through the use of materialshaving lithographic characteristics and performing patterning, forexample, by making exposures. Alternatively, the color filters 60 andthe near-infrared absorption filters 50 can be formed by forming aphotoresist film over an upper material layer, selectively keeping thephotoresist film by lithography, and performing patterning by dryetching or other processing means.

FIG. 13 is a schematic graph illustrating the spectral transmittance ofthe first near-infrared absorption layer. The spectral characteristicsare set in a similar manner to those depicted in FIG. 6, and the centerof the near-infrared light absorption band is set, for example, toapproximately 850 nm. FIG. 14 is a schematic graph illustrating thespectral transmittance of the second near-infrared absorption layer. Inthe case depicted in the drawing, the center of the near-infrared lightabsorption band is shifted by approximately 30 nm toward the shortwavelength side.

The spectral transmittance of the near-infrared absorption filters 50 inthe first embodiment is equivalent to the sum of those depicted in FIGS.13 and 14 and expressed as depicted in FIG. 15.

FIG. 16 is a schematic graph illustrating the overall spectraltransmittance at the center of the imaging area of the imaging elementin a case where the near-infrared absorption filters according to thefirst embodiment are used. Further, FIG. 17 is a schematic graphillustrating the overall spectral transmittance at the periphery of theimaging area of the imaging element in the case where the near-infraredabsorption filters according to the first embodiment are used.

As is obvious from FIGS. 16 and 17, the mixed color component that isobtained when visible light is mixed with near-infrared light does notsignificantly change even when the CRA is increased to shift thenear-infrared light transmission band of the dual-pass filter 70 towardthe short wavelength side. Consequently, a color tone change caused bythe difference in CRA is reduced. This makes it possible to improvescreen uniformity.

The foregoing description assumes that the near-infrared absorptionfilters 50 include two layers. Alternatively, however, the near-infraredabsorption filters 50 may include a single layer. More specifically, thenear-infrared absorption filters 50 may be formed by a single layerhaving two different coloring substances that differ in near-infraredlight absorption characteristics.

Second Embodiment

A second embodiment relates to a camera system according to the presentdisclosure.

The description given in conjunction with the first embodiment statesthat a color difference arises from the difference in CRA when matrixcomputation is performed as indicated in Equation (1) above in a casewhere the near-infrared absorption filters cited as the referenceexample are used.

In the second embodiment, the signal processing section performscomputation by changing a matrix coefficient in accordance with thepositions of the photoelectric conversion sections. The matrixcoefficient is used to perform computation for eliminating the influenceof near-infrared light included in signals from the visible lightphotoelectric conversion section. Consequently, a color differencearising from the difference in CRA is reduced.

A schematic configuration diagram of the camera system 2 according tothe second embodiment is obtained from FIG. 1 by reading the signalprocessing section 300 as the signal processing section 300B and readingthe camera system 1 as the camera system 1B while the near-infraredabsorption filters 50 have a configuration similar to that of thenear-infrared absorption filters cited as the reference example, whichhas been described with reference to FIG. 6.

The description given in conjunction with the first embodiment statesthat the overall spectral transmittance at the center of the imagingarea of the imaging element in the case where the near-infraredabsorption filters cited as the reference example are used is asdepicted in FIG. 9, and that the overall spectral transmittance at apart of the imaging area of the imaging element where the CRA is 30degrees is as depicted in FIG. 10.

In the second embodiment, the coefficient for matrix computation varieswith the CRA in order to cope with spectral transmittance changesresulting from CRA changes.

For example, in a case where the spectral transmittance is as depictedin FIG. 9, matrix computation is performed as indicated in Equation (1)above, as is the case with the first embodiment. Meanwhile, in a casewhere the spectral transmittance is as depicted in FIG. 10, thecoefficient value is changed in accordance with the CRA, and matrixcomputation is performed as indicated in Equation (2) below in order toobtain the corrected red light signal R_(cvt), the corrected green lightsignal G_(cvt), the corrected blue light signal B_(cvt), and thecorrected near-infrared light signal IR_(cvt).

$\begin{matrix}{\begin{bmatrix}R_{cvt} \\G_{cvt} \\B_{cvt} \\{IR}_{cvt}\end{bmatrix} = {\begin{bmatrix}1.02 & 0 & 0 & {- 0.35} \\0.02 & 1.01 & 0 & {- 0.35} \\0.03 & 0.01 & 1.00 & {- 0.35} \\{- 0.12} & 0 & {- 0.05} & 1.02\end{bmatrix}\begin{bmatrix}R_{ori} \\G_{ori} \\B_{ori} \\{IR}_{{ori}\;}\end{bmatrix}}} & (2)\end{matrix}$

The result of simulation indicates that the ΔEab difference in a24-color Macbeth chart between a CRA of 0 degrees and a CRA of 30degrees is 11.6 at maximum in patch No. 15 and 1.4 on the average of 24colors. A ΔEab difference of 1.4 represents a sufficiently low level atwhich the color difference is too small to be recognized by the humaneye.

It should be noted that the CRA varies with the position of thephotoelectric conversion section 40 in the imaging element 100, forexample, with the height of an image. In reality, therefore, thefollowing configuration should be used to provide control.

Control should be exercised so as to predetermine optimum matrixcoefficients based on a CRA value in accordance with the overallspectral transmittance based on the CRA value and store thepredetermined optimum matrix coefficients in the form of a table. Then,the signal processing section 300B should perform signal processingafter selecting an optimum matrix coefficient on the basis of an imageheight value corresponding to the photoelectric conversion sections 40in accordance with the relation between the CRA and the image heightvalue of each photoelectric conversion section, which is determined bythe lens specifications for the optical section 200 and thespecifications for the imaging element 100.

Third Embodiment

A third embodiment relates to an imaging element according to thepresent disclosure and to a camera system that uses such an imagingelement.

The first embodiment is configured so that the near-infrared absorptionfilters 50 are selectively disposed on the light incident surfaces ofthe photoelectric conversion sections in correspondence with the visiblelight photoelectric conversion section, and that the near-infrared lightabsorption band provided by the near-infrared absorption filters 50includes the near-infrared light transmission band of the dual-passfilter and extends toward the short wavelength side.

Meanwhile, the third embodiment is configured so as to reduce theangular dependence of the dual-pass filter itself.

A schematic configuration diagram of the camera system 1C according tothe third embodiment is obtained from FIG. 1 by reading the dual-passfilter 70 as the optical filter 70C including the dual-pass filter,reading the imaging element 100 as the imaging element 100C, and readingthe camera system 1 as the camera system 1C while the near-infraredabsorption filters 50 have a configuration similar to that of thenear-infrared absorption filters cited as the reference example, whichhas been described with reference to FIG. 6.

The imaging element 100C in the third embodiment includes anear-infrared absorption layer that is disposed integrally with orseparately from the dual-pass filter. The near-infrared lighttransmission band of the dual-pass filter is sandwiched between firstand second absorption bands for near-infrared light of the near-infraredabsorption layer.

More specifically, the optical filter 70C used in the third embodimentincludes the dual-pass filter having transmission bands for visiblelight and a predetermined range of near-infrared light, and thenear-infrared absorption layer disposed integrally with or separatelyfrom the dual-pass filter. The near-infrared light transmission band ofthe dual-pass filter is sandwiched between the first and secondabsorption bands for near-infrared light of the near-infrared absorptionlayer. The near-infrared absorption layer includes at least twodifferent coloring substances that differ in near-infrared lightabsorption characteristics.

FIG. 18 is a schematic cross-sectional view illustrating a configurationof the optical filter that includes the dual-pass filter and is used inthe third embodiment. In the example of FIG. 18, the near-infraredabsorption layer includes a first near-infrared absorption layer 73 anda second near-infrared absorption layer 74. The first near-infraredabsorption layer 73 includes one of two different coloring substances,and the second near-infrared absorption layer 74 includes the remainingone of the two different coloring substances.

The optical filter 70C including the dual-pass filter includes a basematerial 71 including, for example, glass, the first infrared absorptionlayer 73, the second infrared absorption layer 74, a cutoff bandabsorption layer 72, and dielectric multilayer films 75 (75A, 75B) thatforms a spectrum having a wavelength region not apparently exhibitedeven in the case of shifting toward the short wavelength side. Thecutoff band is typically a band having a wavelength of 650 to 750 nm. Inthe example of the drawing, the dielectric multilayer films are disposedon both surfaces of the substrate from the viewpoint of reducing thewarp of the base material 71. It should be noted that the dielectricmultilayer films 75 may have anti-reflective characteristics in order toreduce surface reflection. Further, for example, the base material 71may include a transparent resin material with a cutoff band absorptioncoloring substance kneaded into the base material.

FIG. 19 is a schematic graph illustrating the spectral transmittance ofa first infrared absorption layer included in the optical filterincluding the dual-pass filter. The center of the near-infrared lightabsorption band is set, for example, to approximately 800 nm. FIG. 20 isa schematic graph illustrating the spectral transmittance of a secondinfrared absorption layer included in the optical filter including thedual-pass filter. The center of the near-infrared light absorption bandis set, for example, to approximately 900 nm.

FIG. 21 is a schematic graph illustrating the spectral transmittance ofthe optical filter that includes the dual-pass filter and is used in thethird embodiment. Dual-pass characteristics exhibited by the cutoff bandabsorption layer and the dielectric multilayer films are substantiallysimilar to those in the first embodiment.

As depicted in FIG. 21, the near-infrared light transmission band basedon the dual-pass characteristics is sandwiched between the near-infraredlight absorption band of the first infrared absorption layer (the firstabsorption band) and the near-infrared light absorption band of thesecond infrared absorption layer (the second absorption band).Therefore, even when the near-infrared light transmission band of thedielectric multilayer films is shifted toward the short wavelength sidedue to oblique incidence of light rays, the spectral characteristicsrarely exhibit apparent changes due to the first and second infraredabsorption layers, which are not dependent on angles, and the amount ofnear-infrared light entering the visible light photoelectric conversionsection 40 does not significantly change. Consequently, a color tonechange caused by the difference in CRA is reduced. This makes itpossible to improve screen uniformity.

The optical filter 70C including the dual-pass filter in the thirdembodiment need not always have an integral configuration. Modificationsof the third embodiment are described below.

FIG. 22 is a schematic partial end view of the imaging element that ispresented to illustrate a first modification of the third embodiment.FIG. 23 is a schematic partial end view of the imaging element that ispresented to illustrate a second modification of the third embodiment.FIG. 24 is a schematic partial end view of the imaging element that ispresented to illustrate a third modification of the third embodiment.

In the above-mentioned modifications, the upper surface of the on-chiplens of the imaging element is planarized by a low-refractive-indexmaterial. A coating film is formed over the upper surface of thelow-refractive-index material or a coating film is formed over the uppersurface of seal glass that is attached to the upper surface of thelow-refractive-index material.

FIG. 22 depicts a configuration in which infrared absorption layers areformed over the planarized upper surface of the imaging element and acutoff band absorption layer and a dielectric multilayer film, which areincluded in the dual-pass filter, are formed on the base material.

FIG. 23 depicts a configuration in which the dielectric multilayer filmis formed on the base material although the dual-pass filter includesthe cutoff band absorption layer and the dielectric multilayer film, anda different layer including the cutoff band absorption layer is formedover the planarized upper surface of the imaging element.

FIG. 24 depicts an example in which the dielectric multilayer film isformed on the base material although the dual-pass filter includes thecutoff band absorption layer and the dielectric multilayer film, and adifferent layer is formed over the upper surface of the seal glassattached to the imaging element. It should be noted that, although notdepicted, all the layers may be formed over the upper surface of theseal glass.

Individual layers forming the optical filter 70C including the dual-passfilter should be disposed in an appropriate manner from the viewpoint ofcustomizability based on production and use and from the viewpoint, forexample, of process resistance of constituent materials.

The above description assumes that there are two near-infraredabsorption layers. Alternatively, however, there may be only onenear-infrared absorption layer. More specifically, there may be only onenear-infrared absorption layer including two different coloringsubstances that differ in near-infrared light absorptioncharacteristics.

Fourth Embodiment

A fourth embodiment also relates to an imaging element according to thepresent disclosure and to a camera system that uses such an imagingelement.

The fourth embodiment is similar in configuration to the firstembodiment except that the color filters and the near-infrared filtersare disposed in a different manner. A schematic configuration diagram ofthe camera system 1D according to the fourth embodiment is obtained fromFIG. 1 by reading the imaging element 100 as the imaging element 100Dand reading the camera system 1 as the camera system 1D.

For ease of understanding, first of all, the arrangement, for example,of the color filters and near-infrared absorption filters in the firstembodiment will be described.

FIG. 25 are schematic plan views illustrating the arrangement of thecolor filters and near-infrared absorption filters in the firstembodiment. FIG. 25A is a schematic plan view illustrating thearrangement of the color filters in the first embodiment. FIG. 25B is aschematic plan view illustrating the arrangement of the near-infraredabsorption filters in the first embodiment. FIG. 25C is a schematic planview illustrating the arrangement of the photoelectric conversionsections that are involved in the acquisition of a near-infrared imagein the first embodiment.

The color filters 60 depicted in FIG. 25A are designated by the signs“R,” “G,” “B,” and “IR,” which respectively represent red, green, blue,and near-infrared light filters. This also holds true for thelater-described other drawings. As depicted in FIG. 25A, on the basis ofthe Bayer arrangement in which one red pixel, two green pixels, and oneblue pixel are formed into a group, the color filters 60 are arrayed byreplacing one of a pair of green color filters with a near-infraredabsorption filter.

As depicted in FIG. 25B, the near-infrared absorption filters 50 aredisposed in correspondence with the visible light photoelectricconversion section 40. More specifically, the near-infrared absorptionfilters 50 are disposed in correspondence with the red, green, and bluecolor filters.

When the above configuration is adopted, the number of near-infraredlight photoelectric conversion sections is ¼ the total number ofphotoelectric conversion sections. Depending on use, however, it isconceivable that the resolution of near-infrared images is insufficient.For example, in a case where the camera system is used for irisauthentication, it is necessary to capture an image of an iris at a highresolution in order to increase the accuracy of authentication. Thetotal number of pixels in the imaging element can be increased to raisethe resolution of near-infrared images. However, an increase in thenumber of pixels enlarges the element size and raises the cost.

The inventors have found that the S/N ratio significantly deterioratesparticularly in the corrected blue light signal when corrected signalsare obtained, during the use of an imaging element having nonear-infrared absorption filter in the visible light photoelectricconversion section, by performing computation in such a manner as tosubtract the output of the near-infrared light photoelectric conversionsection from the output of the visible light photoelectric conversionsection. This is probably because, for example, the amount of a bluecomponent of visible light is small by nature when common ambient lightis used or S/N ratio deterioration caused by computation is significantwhen an image is captured under an illumination light or othernear-infrared light rich environment.

In view of the above circumstances, the fourth embodiment is configuredso that the near-infrared absorption filters 50 are selectively disposedfor the blue light photoelectric conversion section in the visible lightphotoelectric conversion section 40.

FIG. 26 are schematic plan views illustrating the arrangement of thecolor filters and near-infrared absorption filters in the fourthembodiment. FIG. 26A is a schematic plan view illustrating thearrangement of the color filters in the fourth embodiment. FIG. 26B is aschematic plan view illustrating the arrangement of the near-infraredabsorption filters in the fourth embodiment. FIG. 26C is a schematicplan view illustrating the arrangement of the photoelectric conversionsections that are involved in the acquisition of a near-infrared imagein the fourth embodiment.

As depicted in the drawings, the near-infrared absorption filters 50 areselectively disposed for the blue light photoelectric conversion section40. This makes it possible to suppress S/N ratio deterioration caused bycomputation and achieve near-infrared image capture not only with thenear-infrared light photoelectric conversion section but also with thered and green light photoelectric conversion sections. Consequently, thenumber of photoelectric conversion sections contributing tonear-infrared light image capture is ¾ the total number of photoelectricconversion sections. As a result, the resolution of near-infrared imagescan be raised.

FIG. 27 is a schematic partial end view of the imaging element accordingto the fourth embodiment. For convenience of illustration, it is assumedthat red, green, blue, and near-infrared light elements are arrayed in arow. The color filters 60 and the near-infrared absorption filters 50are stacked over the light incident surface of the blue lightphotoelectric conversion section 40. It should be noted that a layer 50Cincluding a transparent material is disposed on the light incidentsurfaces of the red and green light photoelectric conversion sections 40in correspondence with an omitted near-infrared absorption filter 50.

It should be noted that, in the above-described configuration, matrixcomputation should be performed as indicated in Equation (3) below inorder to obtain the corrected red light signal R_(cvt), the correctedgreen light signal G_(cvt), the corrected blue light signal B_(cvt), andthe corrected near-infrared light signal IR_(cvt).

$\begin{matrix}{\begin{bmatrix}R_{cvt} \\G_{cvt} \\B_{cvt} \\{IR}_{cvt}\end{bmatrix} = {\begin{bmatrix}1.02 & 0 & 0 & {- 1.00} \\0.02 & 1.01 & 0 & {- 1.00} \\0.03 & 0.01 & 1.00 & {- 0.20} \\{- 0.12} & 0 & {- 0.05} & 1.02\end{bmatrix}\begin{bmatrix}R_{ori} \\G_{ori} \\B_{ori} \\{IR}_{{ori}\;}\end{bmatrix}}} & (3)\end{matrix}$

It should be noted that a near-infrared image without components derivedfrom visible light and near-infrared light among ambient light can beacquired by capturing an image while no light is emitted from thenear-infrared light source section, capturing an image while light isemitted from the near-infrared light source section, and determining thedifference between the captured images. It is preferable that a visiblelight image be captured while no light is emitted from the near-infraredlight source section.

Fifth Embodiment

A fifth embodiment also relates to an imaging element according to thepresent disclosure and to a camera system that uses such an imagingelement.

The fifth embodiment is similar in configuration to the first embodimentexcept that the color filters and the near-infrared absorption filtersare disposed in a different manner. A schematic configuration diagram ofthe camera system 1E according to the fifth embodiment is obtained fromFIG. 1 by reading the imaging element 100 as the imaging element 100Eand reading the camera system 1 as the camera system 1E.

In the fifth embodiment, the green light photoelectric conversionsection is set to a higher placement ratio than the other photoelectricconversion sections. FIG. 28 are schematic plan views illustrating thearrangement of the color filters and near-infrared absorption filters inthe fifth embodiment. FIG. 28A is a schematic plan view illustrating thearrangement of the color filters in the fifth embodiment. FIG. 28B is aschematic plan view illustrating the arrangement of the near-infraredabsorption filters in the fifth embodiment. FIG. 28C is a schematic planview illustrating the arrangement of the photoelectric conversionsections that are involved in the acquisition of a near-infrared imagein the fifth embodiment.

When the above-mentioned arrangement scheme is adopted, the number ofgreen light photoelectric conversion sections 40 acquiring luminanceinformation is ½ the total number of photoelectric conversion sections.As a result, the resolution of visible light images can be equivalent tothe resolution achieved by the common Bayer arrangement. Thecross-sectional structure is similar to the one indicated in FIG. 12.

It should be noted that the near-infrared absorption filters 50 may bedisposed only on the light incident surface of the blue lightphotoelectric conversion section 40, as is the case with the fourthembodiment. FIG. 29 are diagrams illustrating the arrangement of thecolor filters and near-infrared absorption filters in the fifthembodiment in a case where the arrangement of the near-infraredabsorption filters is limited. FIG. 29A is a schematic plan viewillustrating the arrangement of the color filters. FIG. 29B is aschematic plan view illustrating the arrangement of the near-infraredabsorption filters. FIG. 29C is a schematic plan view illustrating thearrangement of the photoelectric conversion sections that are involvedin the acquisition of a near-infrared image.

Sixth Embodiment

A sixth embodiment also relates to an imaging element according to thepresent disclosure and to a camera system that uses such an imagingelement.

The sixth embodiment is similar in configuration to the first embodimentexcept that a near-infrared image is captured by using a white lightphotoelectric conversion section. A schematic configuration diagram ofthe camera system 1F according to the sixth embodiment is obtained fromFIG. 1 by reading the imaging element 100 as the imaging element 100Fand reading the camera system 1 as the camera system 1F.

In the sixth embodiment, the near-infrared light photoelectricconversion section includes the white light photoelectric conversionsection. FIG. 30 are schematic plan views illustrating the arrangementof the color filters and near-infrared absorption filters in the sixthembodiment. FIG. 30A is a schematic plan view illustrating thearrangement of the color filters in the sixth embodiment. FIG. 30B is aschematic plan view illustrating the arrangement of the near-infraredabsorption filters in the sixth embodiment. FIG. 30C is a schematic planview illustrating the arrangement of the photoelectric conversionsections that are involved in the acquisition of a near-infrared imagein the sixth embodiment.

The color filters 60 that are depicted in FIG. 30A and designated by thesign “W” include, for example, a material that transmits visible lightand near-infrared light. The white light photoelectric conversionsection 40 is sensitive not only to visible light but also tonear-infrared light. Therefore, a near-infrared imaging signal can beobtained by subtracting the outputs of the red, green, and blue lightphotoelectric conversion sections from the output of the white lightphotoelectric conversion section.

It should be noted that the near-infrared absorption filters 50 may bedisposed only on the light incident surface of the blue lightphotoelectric conversion section 40, as is the case with the fourthembodiment. FIG. 31 are diagrams illustrating the arrangement of thecolor filters and near-infrared absorption filters in the sixthembodiment in a case where the arrangement of the near-infraredabsorption filters is limited. FIG. 31A is a schematic plan viewillustrating the arrangement of the color filters. FIG. 31B is aschematic plan view illustrating the arrangement of the near-infraredabsorption filters. FIG. 31C is a schematic plan view illustrating thearrangement of the photoelectric conversion sections that are involvedin the acquisition of a near-infrared image.

Seventh Embodiment

A seventh embodiment relates to a modification of the cross-sectionalstructure of the imaging element.

FIG. 32 is a schematic partial end view of the imaging element in theseventh embodiment.

The cross-sectional structure depicted in FIG. 12, which is referencedin conjunction with the first embodiment, indicates that thenear-infrared absorption filters 50 are stacked over a planarized film.This may increase the thickness of the imaging element. Accordingly, theseventh embodiment is configured so that the near-infrared absorptionfilters 50 are partly embedded in the planarized film.

At least a part of the near-infrared absorption filters 50 (or morespecifically, the first near-infrared absorption layer 50A) is embeddedinto the opening in the light-shielding layer 30 that separatesneighboring photoelectric conversion sections 40. More specifically,after the planarized film is formed, the near-infrared absorptionfilters should be embedded into the opening that is formed in theplanarized film by using a well-known patterning technique.

Eighth Embodiment

An eighth embodiment relates to a modification of the cross-sectionalstructure of the imaging element.

FIG. 33 is a schematic partial end view of the imaging element in theeighth embodiment.

In order to prevent color mixture, a shallow trench structure 11 isformed on the substrate on which the photoelectric conversion sections40 are mounted. The shallow trench structure 11 separates theneighboring photoelectric conversion sections 40. The shallow trenchstructure 11 is formed by making a groove in the substrate 10 by using,for example, the RIE technology, and embedding a metal or dielectricmaterial into the groove. This reduces the color mixture in thesubstrate that is caused by oblique incident light rays.

While embodiments of the present disclosure have been described indetail, it should be understood that the present disclosure is notlimited to the foregoing embodiments, and that various modifications canbe made on the basis of the technical idea of the present disclosure.For example, the numerical values, structures, substrates, rawmaterials, and processes mentioned in conjunction with the foregoingembodiments are merely illustrative and not restrictive. For example,other numerical values, structures, substrates, raw materials, andprocesses may be used as needed.

It should be noted that the technology provided by the presentdisclosure may adopt the following configurations.

[A1]

An imaging element including:

a plurality of photoelectric conversion sections that are arrayed on asubstrate to receive light incident through a dual-pass filter havingtransmission bands for visible light and a predetermined range ofnear-infrared light,

in which the photoelectric conversion sections include a visible lightphotoelectric conversion section and a near-infrared light photoelectricconversion section, and

the visible light photoelectric conversion section includes a red lightphotoelectric conversion section, a green light photoelectric conversionsection, and a blue light photoelectric conversion section.

[A2]

The imaging element as described in [A1] above, in which the red lightphotoelectric conversion section, the green light photoelectricconversion section, the blue light photoelectric conversion section, andthe near-infrared light photoelectric conversion section are arrayed ina mosaic pattern.

[A3]

The imaging element as described in [A1] or [A2] above, in which thegreen light photoelectric conversion section is set to a higherplacement ratio than the other photoelectric conversion sections.

[A4]

The imaging element as described in any one of [A1] to [A3] above, inwhich the near-infrared light photoelectric conversion section includesa white light photoelectric conversion section.

[A5]

The imaging element as described in any one of [A1] to [A4] above, inwhich a shallow trench structure for separating neighboringphotoelectric conversion sections is formed on the substrate.

[A6]

The imaging element as described in any one of [A1] to [A5] above,

in which a near-infrared absorption filter is selectively disposed on alight incident surface of the photoelectric conversion sections incorrespondence with the visible light photoelectric conversion section,and

setup is performed so that a near-infrared light absorption bandprovided by the near-infrared absorption filter includes a near-infraredlight transmission band of the dual-pass filter and extends toward ashort wavelength side.

[A7]

The imaging element as described in [A6] above, in which thenear-infrared light absorption band provided by the near-infraredabsorption filter is set to include the near-infrared light transmissionband of the dual-pass filter even in a case where the near-infraredlight transmission band is shifted toward the short wavelength side dueto oblique light incidence.

[A8]

The imaging element as described in [A7] above, in which thenear-infrared absorption filter includes at least two different coloringsubstances differing in near-infrared light absorption characteristics.

[A9]

The imaging element as described in [A8] above, in which thenear-infrared absorption filter includes a first near-infraredabsorption layer and a second near-infrared absorption layer, and thefirst near-infrared absorption layer includes one of the two differentcoloring substances, and the second near-infrared absorption layerincludes the remaining one of the two different coloring substances.

[A10]

The imaging element as described in [A8] above, in which thenear-infrared absorption filter includes a single layer.

[A11]

The imaging element as described in any one of [A6] to [A10] above, inwhich the near-infrared absorption filter is selectively disposed incorrespondence with the red light photoelectric conversion section, thegreen light photoelectric conversion section, and the blue lightphotoelectric conversion section.

[A12]

The imaging element as described in any one of [A6] to [A10] above, inwhich the near-infrared absorption filter is selectively disposed forthe blue light photoelectric conversion section in the visible lightphotoelectric conversion section.

[A13]

The imaging element as described in any one of [A6] to [A12] above, inwhich a color filter and the near-infrared absorption filter are stackedover the light incident surface of the visible light photoelectricconversion section.

[A14]

The imaging element as described in [A13] above, in which at least apart of the near-infrared absorption filter is embedded into an openingin a light-shielding layer separating neighboring photoelectricconversion sections.

[A15]

The imaging element as described in any one of [A1] to [A5] above,further including:

a near-infrared absorption layer that is disposed integrally with orseparately from the dual-pass filter,

in which the near-infrared light transmission band of the dual-passfilter is sandwiched between a first absorption band and a secondabsorption band, the first absorption band and the second absorptionband being provided for near-infrared light in the near-infraredabsorption layer.

[A16]

The imaging element as described in [A15] above, in which thenear-infrared absorption layer includes at least two different coloringsubstances differing in near-infrared light absorption characteristics.

[A17]

The imaging element as described in [A16] above,

in which the near-infrared absorption layer includes a firstnear-infrared absorption layer and a second near-infrared absorptionlayer, and

the first near-infrared absorption layer includes one of two differentcoloring substances, and the second near-infrared absorption layerincludes the remaining one of the two different coloring substances.

[A18]

The imaging element as described in [A16] above, in which thenear-infrared absorption layer includes a single layer containing twodifferent coloring substances differing in near-infrared lightabsorption characteristics.

[A19]

A camera system including:

an optical section that forms an image of a subject;

an imaging element that includes a plurality of photoelectric conversionsections, the photoelectric conversion sections being arrayed on asubstrate to receive light incident through a dual-pass filter havingtransmission bands for visible light and a predetermined range ofnear-infrared light; and

a signal processing section that processes signals from thephotoelectric conversion sections,

in which the photoelectric conversion sections include a visible lightphotoelectric conversion section and a near-infrared light photoelectricconversion section, and

the signal processing section performs computation after changing amatrix coefficient in accordance with a position of a photoelectricconversion section, the matrix coefficient being used to performcomputation for eliminating an influence of near-infrared light includedin a signal from the visible light photoelectric conversion section.

Further, the technology provided by the present disclosure may adopt thefollowing configurations.

[B1]

An imaging element including:

a plurality of photoelectric conversion sections that are arrayed on asubstrate to receive light incident through a dual-pass filter havingtransmission bands for visible light and a predetermined range ofnear-infrared light,

in which the photoelectric conversion sections include a visible lightphotoelectric conversion section and a near-infrared light photoelectricconversion section, and a near-infrared absorption filter is selectivelydisposed on a light incident surface of the photoelectric conversionsections in correspondence with the visible light photoelectricconversion section, and

setup is performed so that a near-infrared light absorption bandprovided by the near-infrared absorption filter includes a near-infraredlight transmission band of the dual-pass filter and extends toward ashort wavelength side.

[B2]

The imaging element as described in [B1] above, in which thenear-infrared light absorption band provided by the near-infraredabsorption filter is set to include the near-infrared light transmissionband of the dual-pass filter even in a case where the near-infraredlight transmission band is shifted toward the short wavelength side dueto oblique light incidence.

[B3]

The imaging element as described in [B2] above, in which thenear-infrared absorption filter includes at least two different coloringsubstances differing in near-infrared light absorption characteristics.

[B4]

The imaging element as described in [B3] above,

in which the near-infrared absorption filter includes a firstnear-infrared absorption layer and a second near-infrared absorptionlayer, and

the first near-infrared absorption layer includes one of the twodifferent coloring substances, and the second near-infrared absorptionlayer includes the remaining one of the two different coloringsubstances.

[B5]

The imaging element as described in [B3] above, in which thenear-infrared absorption filter includes a single layer.

[B6]

The imaging element as described in any one of [B1] to [B5] above, inwhich the visible light photoelectric conversion section includes a redlight photoelectric conversion section, a green light photoelectricconversion section, and a blue light photoelectric conversion section.

[B7]

The imaging element as described in [B6] above, in which the red lightphotoelectric conversion section, the green light photoelectricconversion section, the blue light photoelectric conversion section, andthe near-infrared light photoelectric conversion section are arrayed ina mosaic pattern.

[B8]

The imaging element as described in [B6] or [B7] above, in which thenear-infrared absorption filter is selectively disposed incorrespondence with the red light photoelectric conversion section, thegreen light photoelectric conversion section, and the blue lightphotoelectric conversion section.

[B9]

The imaging element as described in [B6] or [B7] above, in which thenear-infrared absorption filter is selectively disposed for the bluelight photoelectric conversion section in the visible lightphotoelectric conversion section.

[B10]

The imaging element as described in any one of [B6] to [B9] above, inwhich the green light photoelectric conversion section is set to ahigher placement ratio than the other photoelectric conversion sections.

[B11]

The imaging element as described in any one of [B1] to [B10] above, inwhich the near-infrared light photoelectric conversion section includesa white light photoelectric conversion section.

[B12]

The imaging element as described in any one of [B1] to [B11] above, inwhich a color filter and the near-infrared absorption filter are stackedover the light incident surface of the visible light photoelectricconversion section.

[B13]

The imaging element as described in [B12] above, in which at least apart of the near-infrared absorption filter is embedded into an openingin a light-shielding layer separating neighboring photoelectricconversion sections.

[B14]

The imaging element as described in any one of [B1] to [B13] above, inwhich a shallow trench structure for separating neighboringphotoelectric conversion sections is formed on the substrate.

[B15]

An imaging element including:

a dual-pass filter having transmission bands for visible light and apredetermined range of near-infrared light;

a near-infrared absorption layer disposed integrally with or separatelyfrom the dual-pass filter; and

a plurality of photoelectric conversion sections arrayed on a substrateto receive light incident through the dual-pass filter,

in which the photoelectric conversion sections include a visible lightphotoelectric conversion section and a near-infrared light photoelectricconversion section, and

the near-infrared light transmission band of the dual-pass filter issandwiched between a first absorption band and a second absorption band,the first absorption band and the second absorption band being providedfor near-infrared light in the near-infrared absorption layer.

[B16]

The imaging element as described in [B15] above, in which thenear-infrared absorption layer includes at least two different coloringsubstances differing in near-infrared light absorption characteristics.

[B17]

The imaging element as described in [B16] above,

in which the near-infrared absorption layer includes a firstnear-infrared absorption layer and a second near-infrared absorptionlayer, and

the first near-infrared absorption layer includes one of two differentcoloring substances, and the second near-infrared absorption layerincludes the remaining one of the two different coloring substances.

[B18]

The imaging element as described in [B16] above, in which thenear-infrared absorption layer includes a single layer containing twodifferent coloring substances differing in near-infrared lightabsorption characteristics.

[B19]

An optical filter including:

a dual-pass filter having transmission bands for visible light and apredetermined range of near-infrared light; and

a near-infrared absorption layer disposed integrally with or separatelyfrom the dual-pass filter,

in which the near-infrared light transmission band of the dual-passfilter is sandwiched between a first absorption band and a secondabsorption band, the first absorption band and the second absorptionband being provided for near-infrared light in the near-infraredabsorption layer.

[B20]

A camera system including:

an optical section that forms an image of a subject;

an imaging element that includes a plurality of photoelectric conversionsections, the photoelectric conversion sections being arrayed on asubstrate to receive light incident through a dual-pass filter havingtransmission bands for visible light and a predetermined range ofnear-infrared light; and

a signal processing section that processes signals from thephotoelectric conversion sections,

in which the photoelectric conversion sections include a visible lightphotoelectric conversion section and a near-infrared light photoelectricconversion section, and

the signal processing section performs computation after changing amatrix coefficient in accordance with a position of a photoelectricconversion section, the matrix coefficient being used to performcomputation for eliminating an influence of near-infrared light includedin a signal from the visible light photoelectric conversion section.

REFERENCE SIGNS LIST

1 . . . Camera system, 10 . . . Semiconductor substrate, 11 . . .Shallow trench structure, 20 . . . Planarization layer, 30 . . .Light-shielding layer, 40 . . . Photoelectric conversion section, 50 . .. Near-infrared absorption filter, 50A . . . First near-infraredabsorption layer, 50B . . . Second near-infrared absorption layer, 50C .. . Transparent material layer, 60, 60 _(R), 60 _(G), 60 _(B), 60 _(IR). . . Color filter, 61 . . . Transparent material layer, 62 . . .On-chip lens, 70 . . . Dual-pass filter, 70C . . . Optical filterincluding dual-pass filter, 71 . . . Base material, 72 . . . Cutoff bandabsorption layer, 73 . . . First near-infrared absorption layer, 74 . .. Second near-infrared absorption layer, 75, 75 _(A), 75 _(B) . . .Dielectric multilayer film, 100 . . . Imaging element, 200 . . . Opticalsection, 300 . . . Signal processing section, 400 . . . Near-infraredlight source section

The invention claimed is:
 1. An imaging element comprising: a substrate;a first layer including a red color filter, a green color filter, and ablue color filter; a plurality of photoelectric conversion sectionsarrayed on the substrate, the plurality of photoelectric conversionsections configured to receive light incident through dielectricmultilayer films, the photoelectric conversion sections including: a redlight photoelectric conversion section corresponding to the red colorfilter, a green light photoelectric conversion section corresponding tothe green color filter, a blue light photoelectric conversion sectioncorresponding to the blue color filter, and a white light photoelectricconversion section; a planarization layer; a near-infrared absorptionfilter; and a light-shielding layer including an opening, wherein thelight-shielding layer separates neighboring photoelectric conversionsections, wherein at least a part of the near-infrared absorption filteris embedded into the opening of the light-shielding layer.
 2. Theimaging element according to claim 1, wherein the dielectric multilayerfilms comprise several tens of layers.
 3. The imaging element accordingto claim 1, wherein the red light photoelectric conversion section, thegreen light photoelectric conversion section, the blue lightphotoelectric conversion section, and the white light photoelectricconversion section are arrayed in a mosaic pattern.
 4. The imagingelement according to claim 1, wherein the green light photoelectricconversion section is set to a higher placement ratio than otherphotoelectric conversion sections.
 5. The imaging element according toclaim 1, wherein a shallow trench structure for separating neighboringphotoelectric conversion sections is formed on the substrate.
 6. Theimaging element according to claim 1, wherein the near-infraredabsorption filter is selectively disposed on a light incident surface ofthe photoelectric conversion sections in correspondence with the redlight photoelectric conversion section, the green light photoelectricconversion section, and the blue light photoelectric conversion section.7. A biometric authentication camera comprising: a substrate; a firstlayer including a red color filter, a green color filter, and a bluecolor filter; a plurality of photoelectric conversion sections arrayedon the substrate, the plurality of photoelectric conversion sectionsconfigured to receive light incident through dielectric multilayerfilms, the photoelectric conversion sections including: a red lightphotoelectric conversion section corresponding to the red color filter,a green light photoelectric conversion section corresponding to thegreen color filter, a blue light photoelectric conversion sectioncorresponding to the blue color filter, and a white light photoelectricconversion section; a planarization layer; a near-infrared absorptionfilter; and a light-shielding layer including an opening, wherein thelight-shielding layer separates neighboring photoelectric conversionsections, wherein at least a part of the near-infrared absorption filteris embedded into the opening of the light-shielding layer.
 8. Thebiometric authentication camera according to claim 7, wherein thedielectric multilayer films comprise several tens of layers.
 9. Thebiometric authentication camera according to claim 7, wherein the redlight photoelectric conversion section, the green light photoelectricconversion section, the blue light photoelectric conversion section, andthe white light photoelectric conversion section are arrayed in a mosaicpattern.
 10. The biometric authentication camera according to claim 7,wherein the green light photoelectric conversion section is set to ahigher placement ratio than other photoelectric conversion sections. 11.The biometric authentication camera according to claim 7, wherein ashallow trench structure for separating neighboring photoelectricconversion sections is formed on the substrate.
 12. The biometricauthentication camera according to claim 7, wherein the near-infraredabsorption filter is selectively disposed on a light incident surface ofthe photoelectric conversion sections in correspondence with the redlight photoelectric conversion section, the green light photoelectricconversion section, and the blue light photoelectric conversion section.13. An imaging device comprising: a substrate; a first layer including ared color filter, a green color filter, and a blue color filter; aplurality of photoelectric conversion sections arrayed on the substrate,the plurality of photoelectric conversion sections configured to receivelight incident through dielectric multilayer films, the photoelectricconversion sections including: a red light photoelectric conversionsection corresponding to the red color filter, a green lightphotoelectric conversion section corresponding to the green colorfilter, a blue light photoelectric conversion section corresponding tothe blue color filter, and a white light photoelectric conversionsection; a planarization layer; a near-infrared absorption filter; alight-shielding layer including an opening, wherein the light-shieldinglayer separates neighboring photoelectric conversion sections, whereinat least a part of the near-infrared absorption filter is embedded intothe opening of the light-shielding layer; and a lens.
 14. The imagingdevice according to claim 13, wherein the dielectric multilayer filmscomprise several tens of layers.
 15. The imaging device according toclaim 13, wherein the red light photoelectric conversion section, thegreen light photoelectric conversion section, the blue lightphotoelectric conversion section, and the white light photoelectricconversion section are arrayed in a mosaic pattern.
 16. The imagingdevice according to claim 13, wherein the green light photoelectricconversion section is set to a higher placement ratio than otherphotoelectric conversion sections.
 17. The imaging device according toclaim 13, wherein a shallow trench structure for separating neighboringphotoelectric conversion sections is formed on the substrate.
 18. Theimaging device according to claim 13, wherein the near-infraredabsorption filter is selectively disposed on a light incident surface ofthe photoelectric conversion sections in correspondence with the redlight photoelectric conversion section, the green light photoelectricconversion section, and the blue light photoelectric conversion section.